Hydraulic shock absorber



jam. H7, @1939. N. s. FOCHT 9 5 HYDRAULIC snocx ABSORBER Original FiledMay 12, 1936 v 3 Sheets-Sheet 1 Jan, 17, 1939. s FQCHT 2,144,583

HYDRAULIC SHOCK ABSORBER Original Filed May 12, 1936 .3 Sheets-Sheet 2"awe/M00 manameht,

Jan. 17, 1939. N s. FOCHT HYDRAULIC SHOCK ABSORBER Original Filed May12, 1936 5 She ets-Sheet s 57 1 :29.10. 85 66 6 05 k 55 705 937 75 T f6'4 68 m "I r L w 66 i l :Y H 87 T/,/ i gwuc nfom a; J wvmafiachi,

a NMMA Patented Jan. 17, 1939 UNITED STATES 2,144,583 HYDRAULIC SHOCKABSORBER Nevin S. Focht, Cleveland, Ohio Application May 12, 1936,Serial No. 79,381

Renewed November 23, 1938 r 17 Claims.

This invention relates to hydraulic shock absorbers of the strut type asdescribed and claimed, for example, in my prior Patent Nos. 2,035,954and 2,036,623, and has generally in view to provide a shock absorber ofthis type embodying various improved features of construction, combination, arrangement and mode of operation of the parts thereof, allcontributing to a shock absorber which is of comparatively lowproduction and maintenance cost and which is exceptionally eifective inabsorbing all shocks to which it may be subjected.

A special object of the invention is to provide in a shock absorber ofthe strut type having a cylinder and a piston, a novel combination ofnovel valves cooperating with each other and with the cylinder andpiston to control the flow of liquid between the pressure chamberswithin the cylinder at opposite sides of the piston so as to regulatethe relative movements of the cylinder and piston to obtain highlyeffective shock absorbing results.

Another special object of the invention is to provide a shock absorberof the strut type having valves of sturdy, simplified construction whichare designed to operate over long periods of time without requiringrepair or adjustment, and which are so mounted in the'shock absorber andso constructed that they may-readily be removed and disassembled forrepair or adjustment purposes whenever the need arises.

Another special object of the invention is to provide simple, effectivemeans to prevent loss of liquid from the shock absorber and to eliminatetherefrom any air which may have been entrapped therein and which, ifallowed to remain therein, might form air pockets adversely afiectingthe operation of the shock absorber.

With the foregoing and other objects in view, which will become morefully apparent as the nature of the invention is better understood, thesame consists in the novel features of construction, combination andarrangement of parts as will be hereinafter more fully described,illustrated in the accompanying drawings and defined in the appendedclaims.

In the drawings, wherein like characters of reference denotecorresponding parts in the different views:

Figure l is a central, longitudinal section through a shock absorberembodying the improved features of the invention.

Figure 2 is an enlarged central, longitudinal section through the pistonand the rebound control valve illustrating the normal status of theliquid metering pin of said valve.

Figure 3 is a view similar to Figure 2 illustrating an intermediateposition of the liquid metering pin of the rebound control valve. 5

Figure 4 is a view similar to Figure 2 illustrating another position ofthe liquid metering pin of the rebound control valve.

Figure 5 is an enlarged central, longitudinal section through thecompression control valve. 10

Figure 6 is a detail perspective view of the metering pin.

Figures 7 and 8 are cross sections on the lines 1-! and 8-8 of Figures 2and 5, respectively.

Figure 9 is a sectional view illustrating an improved universal jointmounting means for the ends of the shock absorber.

Figure 10 is a detail sectional view illustrating an altemative-form ofvalve for use in the present shock absorber.

Figure 11 is a cross section on the line ||--ll of Figure 10; and

Figure 12 is a perspective view of the liquid metering valve shown inFigure 10.

Referring to the drawings in detail, it will be observed that thepresent shock absorber is of the strut type illustrated in my aforesaidprior applications, and that same includes a working cylinder l0 and apiston II for connection, respectively, with any desired pair ofrelatively movable elements, such, for example, as the axle and thechassis of a motor vehicle.

- While the present shock absorber may be disposed for operation eithervertically or horizontally or at any desired inclination, it will beassumed for purposes of simplifying the present description, to bedisposed vertically.

Concentric with and surrounding the cylinder I0 is a tube l2 which is ofsomewhat greater internal diameter than the external diameter of saidcylinder. Similarly, a casing l3 of somewhat greater internal diameterthan the external diameter of the tube I2 is disposed in concentricsurrounding relationship to said tube. The cylinder, tube and easing areclosed at their ends by upper and lower heads l4 and I 5, respectively,the tube I 2 in the present instance being threaded at its ends intosaid heads and the latter being provided with counter-boresaccommodating the ends of the cylinder l0, and with exterior, slightlytapered and shouldered surfaces with which are engaged the end portionsof the casing I3. The

' tube It, by being threaded into the heads, connects them together andmaintains the cylinder l0 and the casing I3 clamped therebetween. In

this connection and as will later become apparent, it is not necessaryto remove either of the present heads H or IE to afford access to any ofthe working parts of the present shock absorber. Consequently,exceptionally rigid, liquid-tight, taper-fit or other suitable jointsmay be provided between said heads l4 and I5 and the ends of thecylinder l and the casing l3,

Because of the concentric, spaced apart relationship of the cylinder l0,tube l2 and casing l3 a liquid passageway, designated as I6, is providedbetween said cylinder and said tube and a liquid reservoir, designatedas I1, is provided between said tube and said casing.

The piston H is reciprocable within the cylinder l0 and in its normalposition is disposed approximately midway between the heads l4 and I5,dividing the cylinder into upper and lower pressure chambers designatedas a and I), respectively. Extending upwardly from said piston throughthe chamber a and the head I4 is a piston rod l8 which, at its upperend, carries a lug IQ for connection with one of the relatively movableelements, such as the chassis of l a vehicle, movements .of which are tobe controlled by the shock absorber. Similarly, the lower head I isprovided with a lug 20 or is otherwise suitably formed, oralternatively, the body of the shock absorber is suitably formed forconnection with the other of the elements, such as a vehicle axle,movements of which are to be controlled by the shock absorber.

The head l4, upwardly of the shoulder against which seats the upper endof the cylinder ID,

has a bore 2| forming a continuation of the bore 01' said cylinder.Upwardly of this bore 2|, which may be of any suitable length, the headis counterbored as indicated at 22, thereby providing an upwardly facingshoulder 23 outwardly of the bore 2| at the top thereof. The counterbore22 does not extend to the top of the head ll but itself is co terboredas indicated at 24, thereby providmg a shoulder 25 outwardly of thecounterbore 22 at the top thereof. As shown, the second counterboreopens through the top of the head and is internally threaded.

, shoulders is a packing member 21.

Within the head I4 is a removable cylinder head 26 having a bottomportion closely fitting the bore 2| and a top portion of greaterdiameter closely fitting the counterbore 22. Due to the differentdiameters of said portions, a shoulder is formed at the bottom of thetop portion and overlying the shoulder 23. Between said Above theremovable cylinder head 26, the head 14 has engaged therewith a cylinderhead retaining nut 26. An upper part of this nut is threaded into thecounterbore '24 and a lower part thereof is disposed within thecounterbore 22 against the top of the removable cylinder head, therebysecuring the latter within the head l4 and maintaining the packingwasher 26 compressed so that no leakage of liquid may occur between thehead II and the removable cylinder head 26. At the bottom of the upperpart of the nut 26 is a. shoulder which overlies the shoulder 25.Between said shoulders is a packing washer 29 which is maintainedcompressed by said nut so that no liquid may escape around the latter.

In the bottom portion of the removable cylinder head 26 is acentral bore30 and in the upper part of the 'nut 28 is a central bore 3|. The pistonrod l8 extends through the bores 30 and 3| and neatly fits the lastmentioned bor On the other hand, the bore 30 is either of slightlygreater diameter than the piston rod, or is grooved longitudinally, sothat a small amount of liquid and any air contained in the cylinder mayescape therethrough from said cylinder into a chamber 32 formed bycounterbores in the top and bottom portions of the removable cylinderhead 26 and the nut 28, respectively.

In the counterbore of the nut 28 in surrounding relationship to thepiston rod I8 is packing material 33 which is maintained compressed andin sealing engagement with said nut and said piston rod by an expansioncoil spring 34 seated at its bottom against the shoulder at the bottomof the counterbore in the removable cylinder head and at its top againstthe bottom of said packing.

The top portion of the removable cylinder head 26 is of reduced externaldiameter to provide an annular space between said portion and the wallof the counterbore 22, and in the upper edge, or through the upper partof said head are formed grooves or ducts affording communication betweenthe chamber 32 and said annular space. The head I4 is grooved andprovided with ducts 35 affording communication between said annularspace and the liquid reservoir l1. Therefore, the chamber 32 is incommunication with said reservoir.

Whenever the piston II and the head H are moved toward each other, orwhenever for any other reason pressure is developed in the chamber a, asmall amount of liquid andany air contained in the cylinder l0 escapesthrough the bore 30 into the chamber 32. Since very little liquid mayescape through said bore 30, and since the chamber 32 is incommunication with the reservoir [1, said chamber never is subjected tohigh pressure and the packing material 33 therefore serves effectivelyto prevent any loss of liquid through the bore 3|. Moreover, any liquidescaping through the bore 30 into the chamber 32 is free to escape fromsaid chamber to the reservoir l1, and due to the film of liquid betweenthe piston rod l8 and the wall of the bore 30, any air passing from thecylinder l0 into the chamber 32 is prevented from returning to thecylinder. Thus, manifestly, the present packing means for the piston rodl8 serves both to prevent loss of liquid from the shock absorber and topurge the cylinder of any air which may become entrapped therein duringfilling of the shock absorber and which might interfere with properfunctioning of the valves thereof.

The nut 28 is provided at its top with a polygonal head 36 disposedabove the top of the head l4 and the lug I9 is provided in its undersidewith a polygonal recess 31 to receive said head 36. Thus, by firstmoving the lug l9 downwardly over the head 36 and by then rotating saidlug, the nut 28 may be unscrewed from the head 14, thereby permittingready removal of the piston II and the removable cylinder head 26.

To exclude foreign matter from the piston rod l8 and the head it, thelug l9 preferably is provided with a sheath 38 extending downwardlyaround the head I4 and the casing l3. This sheath is of suflicientlength to extend over the head I I when the piston rod I8 is at itsuppermost limit of movement relative to the cylinder Ill.

'The piston I l comprises a cup-like body 33 open at its top and havingside and bottom walls. and a cup 40 threaded into and closing the top ofsaid body and having the lower end of the piston rod [8 threadedtherein. There is thus provided within said piston a chamber 4| which isin constant communication with the chamber a through openings 42 in thecap 40 and in communication with the chamber b throughopenings 43 in thebottom wallof the body 39 under the control of .a valve disk 44.

The valve disk 44 is disposed within the chamber 4| and is guided forvertical movement therein by a flange 45 extending upwardly therefromaround the lower end portion of the piston rod l8 which extendsdownwardly into said chamber. Normally, said disk is urged downwardlyagainst the upper side of the bottom wall of the body 39 in covering andclosing relationship to the openings 43 by a coil spring 46 seating atits bottom against said disk and at its top against the cap 4|].

In the center of the disk 44 is an opening 41 and in the center of thebottom wall of the body 59 is an opening 48. In alignment with theseopenings, the piston rod 3 has a central bore 49 which opens through thebottom thereof and extends upwardly into the same a limited distance. Inthis bore 49 is slidably mounted a metering pin body 59 havingprojecting downwardly from its lower end a metering pin which, towardits lower end, is of progressively increasing sectional area and which,at its lower end, is of suitably less diameter or sectional area thanthe central opening 41 in the valve disk 44. A coil spring 52 interposedbetween the body 50 and the wall defining the top of the bore 49 tendsconstantly to urge said metering pin body downwardly to its normalposition in which it seats at its bottom against the valve disk 44 andthe metering pin 5| extends through the central opening 41 in said diskvalve. As illustrated in Figure 6, the bottom of the body 50 is cut awayat opposite sides, as indicated at 53, or otherwise is suitably formedat its bottom, so that when it is seated against the disk 44 liquid mayflow between the chamber 4| and the cylinder chamber I) through openings54 in the flange 45 and through the openings 41 and 48 around themetering pin 5|.

When the shock absorber is filled with liquid, liquid is contained inthe bore 49. In this connection, in order to provide for rise of themetering pin body 50 and the metering pin 5| at pre-- determined ratesunder predetermined liquid pressures in the chamber 4|, the said body 50is of suitably less diameter than the bore 49, or either said body orthe wall defining the side of the bore 49 is longitudinally grooved, forflow of liquid from said bore. Moreover, in order to provide forincrease in the rate of fiow of liquid from the chamber b through thepiston openings 43 and 42 to the chamber a as the disk valve 44 rises,the bottom portion of the piston chamber is of upwardly increasingsectional area as indicated at 55. a

Obviously, when the piston II is removed from the cylinder I9 the partscontained within said piston are readily accessible for any purposesimply by unscrewing the piston bgdy 39 from the cap 40.

The lower head I5 of the shock absorber has a bore 56 forming a bottomcontinuation of the cylinder I0, and at its bottom said bore is ofreduced diameter and in communication with the reservoir I! throughlateral ducts 51 and longitudinal grooves or ducts 58 in said head.

Directly above the ducts 51 the head I5 is interiorly shouldered, asindicated at 59, and above said shoulder the wall defining the -bore 56is screw-threaded to threadedly receive the lower end portion 60 of avalve body designated generally as 8|. The intermediate portion 62 ofthis valve body is of lesser diameter than its lower, screw threadedportion 69 and its top portion 83 is of lesser diameter than itsintermediate portion 62. Extending through the lower portion 60 of saidvalve body are openings 64 which provide for flow of liquid between thereservoir l1 and the cylinder chamber h under the control of a valve 65in the form of a ring which seats against the top of the portion 60 ofthe valve body and normally is urged to its seat covering and closingthe openings 64 by. a coil spring 56 suitably anchored at its top to theintermediate portion 62 of said valve body.

The lower and intermediate portions of the valve body 6| are chamberedas indicated "at 61 and the top portion 63 of said body is bored asindicated at 68. The Wall defining the chamber 61 is interiorlyscrew-threaded at its bottom and has threadedly engaged therewith a plug69 through which extend openings afiording constant communicationbetween the chamber 61 and the duct 51. 'In said plug 69 is a centralbore H which is closed at its bottom and opens through the top of saidplugj Slidably engaged at its lower end in the bore 1| and extendingupwardly through the chamber 61 into the bore 68 is a valve 12 the upperportion of which neatly fits said bore 68 and the lower portion of whichis of slightly greater diameter than said upper portion to provide ashoulder for engagement with the wall defining the top of the chamber 61to limit upward movement of the valve.

The valve 12 is of closed top, open bottom, hollow construction andnormally is urged to its uppermost limit of movement by a coil spring 13interposed between the same and the plug- 69. Also interposed betweensaid valve 12 and. the plug 69 is a second coil spring 14 which normallyis inactive, but which becomes active to resist downward movement ofsaid valve following a predetermined amount of downward movementthereof.

In the top portion 63 of the valve body 6| are transverse openingsaffording communication between the cylinder chamber b and the bore 68,and in the valve 12 are two exterior annular grooves 16 and l! spacedone above the other and disposed above the openings 15 when the valve isin its normal uppermost position. Formed through the valve and providingcommunication between the interior thereof and the grooves 16 and 11 areopenings 18. Also formed through the valve and providing communication.between its interior and its exterior are openings 19 which, in thenormal uppermost position of the valve, are disposed within and directlyadjacent to the lower end portion of the base 68. In addition, otheropenings 80 are 'formed through the lower end portion of the valve 12 atpoints such that they are disposed directly above the top of the plug 69when the valve is in its normal, uppermost position.

Exteriorly, the top portion 63 of the valve body 6| is suitably formedto be engaged by a wrench which may be inserted through the cylinder l0when the head M, the removable cylinder head 26 and the piston II areremoved. Thus, said valve body 6| may readily be unscrewed and removedfrom the head l5 and when removed, ac-

cess may readily be had to the valve parts simply by unscrewing the plug69.

In the upper portion of the cylinder in at spaced points therealong is aseries of small openings 8| affording restricted communication betweensaid cylinder and the passageway l6, while in the extreme top portion ofsaid cylinder Ill are openings 82 affording free communication betweensaid cylinder and said passageway.

Assuming that the lugs I9 and 20 are connected to the chassis and theaxle, respectively, of a motor vehicle; that the leaf springs of thevehicle are under normal load; that the piston II is in its normalposition approximately midway between the ends of the cylinder I; thatthe valves are in their aforementioned normal positions, and that theshock absorber is charged with oil or other suitable liquid, the samehas four distinct phases of operation; viz. (1) compression abovenormal, as when an. obstruction in a roadway is encountered and thevehicle springs are compressed and the cylinder in is moved upwardlyrelative to the piston l I; (2) rebound above normal, or downwardmovement of the cylinder l0 relative to the piston il followingcompression above normal; (3) rebound below normal, as when a depressionin a roadway is encountered and the vehicle springs are deflected andthe cylinder l0 moves downwardly relative to the piston II; and (4)compression below normal, or upward movement of the cylinder relative tothe piston following rebound below normal."

As compression above normal occurs, the piston H and the head I5 movetoward each other and the liquid in the chamber b is subjected topressure. The check valve 65 being closed, flow of liquid from thechamber b through the openings 64 is prevented. Moreover, although a thepressure of the liquid on top of the valve 12, which value is exposed atits top to the pressure of the liquid in the chamber b, results indownward movement and consequent opening of this valve, not sufficientliquid may escape through this valve, nor through the openings 4| and 41around the metering pin 5|, to permit the piston i I and the head l5 tomove toward each other at a required initialrapid rate. Therefore, thevalve 44 opens and liquid flows o from the chamber b through theopenings 43,

the chamber 4| and the openings 42 into the chamber a, at a ratedetermined by the strength of the spring 46, the areas of the openings43 and 42 and the resistance to upward movement of the valve 44 by themetering pin bodv 50 to permit the piston l I and the head I 5 to movetoward each other at a desired rate.

Due to the presence of the piston rod I! in the chamber a, this chambercannot accommodate all of the liquid that is forced from the chamber b.The excess liquid therefore is forced through the valve at the bottom ofthe shock absorber into the reservoir H. In this connection. the rate offlow of the liquid through the latter valve is dependent, of course,upon the suddenness of the movement of the piston II and the head I!toward each other and the pressure generated in the chamber b.' If themovement and the pressure generated are normal, the valve 12 is forceddownwardly until the groove 16 aligns with the openings 15, at whichpoint the spring 14 becomes eflective to resist further downwardmovement of said valve 12. flows through said openings 15 into thegroove It, through the openings 18 into the interior of Thereupon,liquid the valve 12, from said valve through the openings I9 into thechamber 61, and from said chamber through the openings and the ducts 5'!and 58 into the liquid reservoir [1 at a rate determined by the areas ofthe openings 18. If, on the other hand, the movement is sudden and thepressure is high, the valve 12 is moved farther downwardly, against theresistance of both springs 13 and 14, until the groove 11 becomesaligned with the openings 15. The flow of liquid then is the same asjust set forth, except that it is more rapid due to the fact that thegroove 11 and the related openings 18 are wider and of greater area,respectively, than the groove 16 and its related openings 18. Duringinitial downward movement of the valve 12, liquid within said valve andthe chamber ll escapes through the openings 80.

Regarding both normal and exceptionally sudden movements of the pistonII and the head l5 toward each other, it will be noted that the upwardlyincreasing sectional area of the bottom portion of the chamber 4iprovides for an increasing rate of flow of liquid through the piston IIas the amount of opening movement of the valve 46 is increased, which inconjunction with the valve 12, obviously provides for smoothness inchecking shocks which produce the "compression above normal" phase ofoperation of the shock absorber.

As the rebound above normal" phase of operation of the shock absorberoccurs following the compression above normal phase of operationthereof, the piston II, in its return to its normal position, movestoward the head l4, thereby subjecting the liquid in the chamber a topressure. The liquid obviously cannot flow from the chamber a to thechamber 1) except through the piston II, and it cannot flow through theopenings 42, 43 of said piston because of the immediate closing of theopenings 43 by the valve disk 44. Therefore, the liquid is required toilow through the openings 54 in the flange 45 of the valve disk 44 andaround the metering pin 5| through the openings 41 and 48 into thechamber b. Since. however, not enough liquid is contained in the chambera to fill the chamber 17, the valve 65 opens and a suflicient quantityof liquid is drawn from. the reservoir I 1 into the chamber 17 tomaintain the same filled.

Although the valve disk 44 closes immediately upon reversal of the shockabsorber from its compression above normal phase of operation to its"rebound above normal phase of operation, the metering pin body 50 andthe metering pin can return to their normal positions, even though urgedby the spring 52, only as fast as liquid can enter the bore or dash-potchamber 49. Therefore, the return of the metering pin to its normalposition is gradual. and at a rate determined by the strength of thespring 52, the provision for flow of liquid to and from the bore orchamber 49, and the diiference in the end areas of the metering pin bodywhich are subjected to liquid pressure above the disk valve 44. Thus, asthe piston i I moves upwardly, the el fective area of the opening 41initially is restricted, but increases with upward movement of thepiston. In the case of application of the shock absorber to a motorvehicle, this means, of course, that upon rebound of the vehicle springsfollowing compression thereof, the flow of liquid from the chamber a tothe chamber 11 is at an increasing rate so as to effectively resistrapid expansion of the vehicle springs when they are most highlyenergized and to permit their more rapid expansion as their energydecreases. The vehicle body thus is relieved of shock due to rebound ofthe vehicle springs.

The rebound below normal phase of operation of the shock absorber occurswhenever for any reason the piston H is moved from its normal position,or approximately its normal position, toward the head I4. Uponinitiation of such movement of the piston, liquid flows only through themetering pin controlled opening 41 and liquid to maintain the chamber bfilled is drawn from the reservoir through the openings 64. Therefore,initial movement of the piston H from its. normal position toward thehead I4 is effectively checked. However, as the piston moves toward thehead l4, it moves above one or more of the openings 8|, and therebyestablishes direct communication between the passageway l6 and from saidpassageway into the chamber b through the opening, or openings 8! belowthe piston. In this connection, since the resistance to -fiow of theliquid from the chamber a to the chamber b obviously decreases as thepiston moves toward the head M, the resistance to movement of the pistontoward said head decreases as it moves toward said head. Consequently,the piston H is eased toward the head l4 first gradually and then at anaccelerated rate in a desired manner to obtain smooth checking orabsorption of shocks which produce the rebound below normal phase ofoperation of the shock absorber. In the case of application of the shockabsorber to a motor vehicle, this means, of course, that upon passage.of the vehicle over a depression in the road surface, the wheels arenot permitted to drop suddenly into the depression, but are graduallyeased downwardly initially and only are permitted to move more rapidlydownward as the energy of the vehicle springs is expended. Thus, "pulldown of the vehicle chassis and body is avoided and again the latter arerelieved of any shock.

Following the rebound below normal phase of operation there occurs thecompression below norma phase of operation characterized by returnmovement of the piston H to its normal position. As the piston movesfrom a position above its normal position toward .the head I 5, liquidflows from the chamber b through the openings 8| below the piston intothe passageway i6 and through said passageway and the openings 82 andalso the openings 8| above the piston, into the chamber a. Obviously,the freedom of such flow progressively decreases due to the progressivecovering by the piston of the openings 8| therebelow. At the same time,thevalve disk 44 rises and some of the liquid flows from the chamber bthrough the piston openings 43 and 42 tothe chamber a. Moreover, anadditional amount of liquid flows from the chamber b' to the chamber athrough the openings 48 and 41 around the metering pin 5|, and since thechamber a cannot accommodate all of the liquid that is forced from thechamber b, the excess liquid is forced through the valve 12 to thereservoir H, all as heretofore set fo th in connection with thecompression above rmal phase of operation of the shock absorbji.Accordingly, the compression below normal phase of operation of theshock absorber is characterized by relatively rapid initial movement andsubsequent progressively retarded movement of the piston II to itsnormal position. In the case of application or the shock absorber to amotor vehicle, this means, of course, that as the distended vehiclesprings return to their normal positions, they as well as the design ofthe various other parts of the present shock absorber may be variedwithin a considerable range to obtain desired operation under particularconditions of installation. In this connection, the shock absorberillustrated is of a design for use on an average motor vehicle to obtainbest riding qualities thereof assuming its normal speed to be in theneighborhood of thirty miles per hour and its high speed to be in theneighborhood of sixty miles per hour. By experiment it has been foundthat the size of the opening 41 and that the length, 'taper andamplitude of movement of the metering pin 5| have definite values toobtain best riding qualities of the vehicle within the approximate speedrange stated. In other words, for maximum vehicle spring compression ata vehicle speed of approximately thirty miles per hour, the metering pin5|, at the moment of fluid reversal or the beginning of the reboundabove normal" phase of operation, will be at a point approximately asillustrated in Figure 4 of the drawings; that is, its lower end portionof greatest diameter will be disposed within the opening 41 reducing theflow of liquid through said opening to a minimum and causing the shockabsorber to hold chassis reactions from spring rebound down to abouteight oscillations per minute.

As the speed of the vehicle is increased to, say sixty miles per hour,its spring reactions naturally will double. Hence, rebound pressure willrise in the shock absorber with corresponding increase in the velocityof the liquid. The metering pin 5| therefore will return toward itsnormal position at increased speed due to the liquid entering the baseor chamber 49, twice as fast as it did at the thirty miles per hourspeed of the vehicle. Hence, for maximum vehicle spring compression at avehicle speed of about sixty miles per hour, the metering pin, at themoment of fluid reversal, will be approximately at the point illustratedin Figure 3. The effective area of the opening 41 then will beapproximately twice as great as it was at a thirty mile per hour speedof the vehicle, and the same holds true proportionally for allintermediate and higher and lower speeds. In other words, the presentshock absorber affords approximately the same degree of proportionalcontrol for substantially all speeds of the vehicle.

As will be understood, the valve 12 is a multistage ofiering either asmaller or larger orifice for liquid escape from the chamber a to governthe pressure of the liquid within said chamber according to the suddenmovement of the piston toward the head I5.

As heretofore stated, the present shock absorber may be mounted eithervertically, horizontally, or at an inclination to the vertical. In thecase of application of the shock absorber to automobiles, it usually ismounted at an inclination to the vertical. Depending upon theinclination of the shock absorber and the amount of movement of thevehicle body toward and from the vehicle axle, there will be producedmore or less rotation of the shock absorber about the axes of itsmounting pins in a vertical plane extending longitudinally of thevehicle. Also, due to side sway of the vehicle body, as when the vehicleis travelling around a ,curve, or when a wheel at one side of thevehicle encounters an obstruction or a depression not encountered by theopposite wheel, there will be produced more or less rotation of theshock absorber relative to its mounting pins in a plane at right anglesto said first mentioned plane. In this connection, Figure 9 of thedrawings illustrates an improved universal joint mounting means for theends of the shock absorber permitting the latter to partake of saidrotary movements separately and simultaneously.

The mounting pins, designated as 88, 88 are of any suitable design to besecured in any suitable manner to the vehicle chassis and the vehicleaxle, respectively, and each terminates in a spherical head 84 havingextending therethrough an opening 85 which flares outwardly from itsmiddle where it is of a diameter corresponding to a related connectingstud 88, one extending axially from the head I4 and the other from thelug I8 or the piston rod I8 through the said opening 85 in the head ofthe related pin 83.

On each stud 88, at opposite sides of the related head 84, respectively,is a pair of dished washers 81 which conform in contour to the head 84and closely engage same, thereby enclosing the flared ends of theopening 85 which contains a suitable lubricant such as graphite. Engagedon each stud 88, between the shock absorber part carrying said stud andthe adjacent washer 81, is a rubber washer 88, while on the outer end ofeach stud 88 is engaged a nut 88 serving to maintain a connected andassembled relationship between the parts of each of the joints.

As is apparent, the joints described not only permit free universalpivotal movements of the shock absorber relative to the vehicle chassisand the vehicle axle, but are of simple construction and capable ofeconomical manufacture; possess long life especially because of therubber washers 88 not being subjected to wiping abrasive action; permitthe use of rubber washers of any desired inherent resilience, and,whenever the necessity arises, may readily be disassembled and equallyas readily reassembled.

In Figure 10 of the drawings is illustrated a novel inertia weightoperable valve which may be used in lieu of the valve illustrated indetail in Figure 5 of the drawings. This valve comprises a hollow body88 which is exteriorly threaded at its bottom to be screwed into thehead ii in the same manner as the valve body 8|, and which is or closedtop, open bottom construction closed atfits bottom by a plug 8i andhaving extending centrally upward from its top wall an extension'82having a bore 83 which is closed at its top and open at its bottom intosaid body 88.

Disposed within the body 88 and constituting to all intentions andpurposes a part thereof is a block 84 the bottom of which is formed witha recess 88 which flares downwardly and outwardly in all directions or,in other-words, is of conical shape, and which accomodates an inertiaweight 88 in the form of a comparatively heavy metal ball which isconstantly urged upwardly into said recess 88 by a spring 81 seated atits top against said ball and at its bottom against the plug 8|. In thetop portion of the block 84, centrally thereof, is a bore 88 which is ofthe same di-- ameter as, and aligned with, the bore 88 and into whichnormally extends the top portion oi the ball 88.

Within the bores 88, 88 is slidably mounted a liquid metering element 88in the form of a spool having an annular exterior recess I88 between itsends and of such length as to aflord open communication between partsIIII extending through the extension 82 and a. top recess I82 in theblock 84, when the spool, which rests at its bottom on the top. of theball 88', is held inits normal uppermost position by said ball.

The spool 88 is of hollow, closed bottom, open top form and contains acoil spring I88 which is seated at its top against the top wall of theextension 82 and tends constantly to urge the spool downwardly, beingprevented from doing so normally, however, because it is weaker than thespring 81.

Formed through the plug 8i, the block 84 and the top wall of the body 88are openings I84, I85 and I88, respectively, for flow of liquid from thereservoir I1 under the control of a check valve I81 arranged to seatdownwardly upon the top wall of the body 88 and normally urged to itsseat by a spring I88. The openings I85 open into the recess I82 in thetop of the block 84 and, therefore, also provide for flow of liquid fromsaid recess to and through the openings I84 to the reservoir I1.

Assuming that the parts of the valve are in their normal positionsillustrated in Figure 10, it is apparent that any sudden compressiondisturbance to which the shock absorber may be subjected with resultantsudden upward movement of the shock absorber, will result, due to theinertia or tendency of the ball 88 to remain stationary, in upwardmovement of the body 88 and the block 84 relative to said ball.Therefore,

the spring I88 will act to move the spool 88 downball will be caused tomove downwardly along the conical under surface of the block with thesame result as flrst mentioned; viz., to permit the spring I88 to movethe spool 88 downwardly to more or less cut oil flow of liquid throughthe openings I8I, depending upon the suddenness of the deceleration oracceleration as the case may be.' Similarly, any sudden sidewisemovement of the vehicle, as when rounding a curve, ob-

viously will produce the same result. In other words, the valveillustrated in Figure 10 operates independently of pressure generatedinthe chamber b and independently of the volume of liquid forced fromsaid chamber, as it controls the flow of liquid from said chamber solelyin response to movement of the ball 88 relative to the block 84 or thebody 88 due to inertia and, of course, according to the amplitude of thecompression shock to which the shock absorber is subjected. Thus, nosingdown" and sidesway, so prevalent with soft front end suspensions ofpresent day automobiles, is greatly minimized. At the same time, allordinary compression shocks are effectively controlled and absorbed, foras fast as compression and rebound oscillations occur, the inertiaweight 88 moves up and down and the effective area of the openings "I iscorrespondingly varied. In this connection it will be understood, ofcourse, that the strength of the spring 91 determines the severity ofshocks necessary to eifect more or less closing and opening of theopenings l l Therefore, by varying the strength of the spring 91, theshock absorber may be.

caused to function to absorb compression shock either quickly, slowly orat any desired rate.

In order to avoid formation within the bore 93 of a vacuum or a liquidabutment which would affect freedom of movement of the spool 99 withinsaid bore, the said spool is provided with openings I09 affordingcommunication between its exterior and its interior. Consequently thepressure inside of said bore and spool is the same as the pressureexteriorly of said spool.

As will be understood, the block 94 is formed separately from the valvebody 90 and is press fitted or otherwise suitably secured within saidbody solely for the sake of economy and convenience in manufacture. Wereit practical to form the block 94 as an integral part of the body 98,this is entirely within the purview of the invention.

Without further description it is thought that the features andadvantages of the invention will be readily apparent to those skilled inthe art, and it will of course be understood, that changes in the form,proportion and minor details of construction may be resorted to, withoutdeparting from the spirit of the invention and scope of the appendedclaims.

I claim:

1. A hydraulic shock absorber comprising a cylinder, a pistonreciprocable within said cylinder and having a normal position betweenthe ends thereof dividing the cylinder into separate pressure chambers,a tube surrounding the cylinder in spaced relationship thereto toprovide a liquid passageway, a casing surrounding said tube in spacedrelationship thereto to provide a liquid reservoir, heads closing theends of said cylinder,

I tube andcasing, a piston rod extending from the piston through one ofsaid heads, the portion of the cylinder between the piston when thelatter is in its normal position and the head through which the pistonrod extends having a longitudinally extending series of openings to besuccessively passed.by the piston when the latter is moved toward saidlast mentioned head to aflord communication between the pressurechambers, a liquid pressure control valve mounted in the other head andcontrolling flow of liquid between the adjacent pressure chamber and thereservoir, and a valve carried by the piston and operable to controlflow of liquid through the piston between the pressure chambers atvariable rates dependent upon the pressure of the liquid.

2. A hydraulic shock absorber comprising a cylinder, a pistonreciprocable within said cylinder and having a normal position betweenthe ends thereof dividing the, cylinder into separate pressure hambers,heads closing the ends of said cylinder, a piston rod extending from thepiston through one of said heads, means prorelative to the disk checkvalve.

sure chambers at variable rates dependent upon the pressure of theliquid.

3. In a hydraulic shock absorber, a cylinder, heads closing the endsthereof, a piston reciprocable within said cylinder and having openingsfor flow of liquid therethrough, a disk check valve controlling saidopenings, said disk check valve having an opening, and a metering pincooperating with the opening in said disk check valve to regulate flowof liquid through the piston when the disk check valve is closed, saidmetering pinbeing mounted to move with the disk check valve when thelatter is opened and upon closing of the disk check valve to be returnedto a predetermined position relative thereto at a rate determined by thepressure of the liquid, said metering pin being shaped to vary theeflective area of the opening in said disk check valve according to theposition of said pin 4. In a hydraulic shock absorber, a cylinder, headsclosing the ends tlrereof, a piston reciprocable within said cylinderand having openings for flow of liquid therethrough, a disk check valvecontrolling said openings, said disk check valve having an opening, anda metering pin cooperating with the opening in said disk check valve toregulate flow of liquid through the piston when the disk check valve isclosed, said metering pin being mounted to remain substandisk checkvalve when the latter closes and to return to its original positionrelative to said disk check valve at a rate determined by the pressureof the liquid and during its return to permit a the opening in the diskcheck valve.

5. In a hydraulic shock absorber, a cylinder, heads closing the endsthereof, a piston reciprocable within said cylinder and having openingsthe latter is opened, and means providing for restricted flow-of liquidinto said dash pot whereby movement of the metering pin to its originalposition relative to the disk valve following closing of the disk valveis at a. rate dependent upon the pressure of the liquid, said meteringpin being shaped to permit progressive increase of the effective area ofthe opening in said disk valve as said pin moves toward its originalposition relative to said disk valve.

- 6. In a hydraulic shock absorber as set forth in claim 3, the pistonhaving a chamber in which the disk valve is disposed, and said chamberhaving side walls surrounding said disk valve and flaring in thedirection of opening movement 01' said valve.

7. In a hydraulic shock absorber, a cylinder, heads closing the ends ofsaid cylinder, a piston reciprocable within said cylinder, meanscontrolling flow of liquid between the cylinder chambers at oppositesides of said piston, a liquid reservoir, and valve means at one end ofsaid cylinder to control the pressure of the liquid in said cylinder andflow of liquid between said tially in the position to which it is movedby the progressively higher rate of flow of liquid through cylinder andsaid reservoir, said valve means including a check valve element tocontrol flow of liquid from the reservoir to the cylinder, and a pistonvalve element to control flow of liquid from the cylinder to thereservoir, said piston valve element being mounted to be moved by theliquid in the cylinder an amount dependent upon the pressure of theliquid and having different sets of openings of different sizes renderedeffective to permit escape of different amounts of liquid from thecylinder to the reservoir dependent upon the amount of movement impartedto said piston valve by the liquid in the cylinder.

8. A hydraulic shock absorber comprising a cylinder, heads closing theends of said cylinder, a piston reciprocable within said cylinder, 9.piston carried valve operable by variations in pressure of the liquid inthe cylinder to vary the rate of flow of liquid through the piston fromone side to the, other side thereof; a liquid reservoir, 9. check valvecontrolling flow of liquid from said reservoir to said cylinder, and apressure relief valve controlling flow of liquid from said cylinder tosaid reservoir and operable by changes in the pressure of the liquid inthe cylinder to vary the rate of flow of the liquid to thereservoir,,said pressure relief valve comprising a hollow casing in oneend of the cylinder separating the latter from the reservoir and havingits interior in communication with the reservoir, said casing having aport affording communication between its interior and the cylinder, apiston slidable in said casing and-exposed at its inner end to besubjected to pressure created in the cylinder so as to be movedoutwardly by such pressure, and spring means urging said pressure reliefvalve piston con-, stantly inward, said piston having a series of portsof difierent sectional areas to successively aline with said casing partfor flow of liquid from the cylinder to the reservoir when said pistonis moved outwardly.

9. The combination as set forth in claim 8 in which the check valve andthe pressure relief valve are combined in a unitary structure mounted inone of the cylinder heads and removable as a unit through the cylinderwhen the other end of the cylinder is opened.

10. The combination as set forth in claim 8 in which oneof the heads hasa removable cylinder head to permit removal of the piston, the checkvalve and the pressure relief valve, and in which the pressure reliefvalve and the check valve are combined in a unitary structure removablymounted in the other head in alignment with the cylinder for removaltherethrough.

11. In a hydraulic shock absorber, a cylinder, a piston reciprocabletherein, an inertia weight mounted for vertical movement and for lateralmovement in all directions relative to said cylinder, and a valvecontrolled by vertical and lateral relative movements between saidcylinder and weight for regulating flow of liquid from the space betweenthe piston and one end of the cylinder proportionately to the amplitudeof the relative movement between the cylinder and the inertia weighw 12.In a hydraulic shock absorber, a cylinder, a piston reciprocabletherein, a hollow valve body carried by said cylinder, a sphericalinertia weight within said body, a' conical surface within said body, aspring urging said inertia weight against said surface, a valve, and aspring urging said valve against said inertia weight in a directionopposite to the direction in which the inerta weight is urged by itsspring, said valve controlling an opening through which liq- 5 uid mayflow from the space between the piston and one end of said cylinder.

13. In a hydraulic shock absorber, a cylinder, a piston reciprocabletherein, a spherical inertia weight carried by said cylinder forvertical movement and for lateral movement in all directions relativethereto, a member carried by said cylinder and having a conical surface.a spring urging said inertia weight against said surface, a valve, and aspring urging said valve against said inertia weight in a directionopposite to the direction in, which said inertia weight is urged by itsspring, said valve controlling an opening through which liquid may flowfrom the space between the piston and one end of said cylinder. 1 14. Ina hydraulic shock absorber, a cylinder, heads closing the ends thereof,a piston reciprocable within said cylinder and having openings for flowof liquid therethrough, a check valve controlling said openings, saidcheck valve having an opening, and a metering pin cooperating with theopening in said check valve to regulate flow of liquid through thepiston when the check valve is closed, said metering pin being mountedto move with the check valve when the latter is opened and upon closingof the check valve to be returned to a predetermined position relativethereto at a rate determined by the pressure of the liquid, saidmetering pin being shaped to vary the effective area of the opening insaid check valve according to the position of said pin relative to thecheck valve.

15. In a hydraulic shock absorber, a cylinder, heads closing the endsthereof, a piston reciprocable within said cylinder and having openingsfor flow of liquid therethrough, a check valve controlling saidopenings. said check valve having an opening, and a metering pincooperating with the opening in said check valve to regulate flow ofliquid through the piston when the check valve is closed, said meteringpin having a normal position relative to said check valve when thelatter is closed and being mounted to be moved by and with said checkvalve when the latter is opened and, when the check valve subsequentlycloses. to return to its normal position relative to said check valve ata rate determined by the pressure of the liquid, said metering pin beingformed so that during its return to its normal position it permits aprogressively higher rate of flow of liquid through the opening in thecheck valve.

16. The combination as set forth in claim 15 comprising dash pot meanscontrolling movement of the metering pin with and relative to N thecheck valve.

17. In a hydraulic shock absorber, a cylinder,

a piston reciprocable therein, a hollow valve body carried by saidcylinder, a conical surface within said body, an inertia weight having a6 spherical surface cooperating with said conical surface, a springurging said inertia weight against said conical surface, and meanscontrolled by movement of said inertia weight relative to said conicalsurface to control flow of 7 liquid from the space between the pistonand one end of the cylinder.

NEVIN S. FOCHT.

